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/**
* @file winmmshim.cpp
* @brief controls volume level of process by intercepting calls to winmm.dll
*
* $LicenseInfo:firstyear=2010&license=viewergpl$
*
* Copyright (c) 2010, Linden Research, Inc.
*
* Second Life Viewer Source Code
* The source code in this file ("Source Code") is provided by Linden Lab
* to you under the terms of the GNU General Public License, version 2.0
* ("GPL"), unless you have obtained a separate licensing agreement
* ("Other License"), formally executed by you and Linden Lab. Terms of
* the GPL can be found in doc/GPL-license.txt in this distribution, or
* online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
*
* There are special exceptions to the terms and conditions of the GPL as
* it is applied to this Source Code. View the full text of the exception
* in the file doc/FLOSS-exception.txt in this software distribution, or
* online at
* http://secondlifegrid.net/programs/open_source/licensing/flossexception
*
* By copying, modifying or distributing this software, you acknowledge
* that you have read and understood your obligations described above,
* and agree to abide by those obligations.
*
* ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
* WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
* COMPLETENESS OR PERFORMANCE.
* $/LicenseInfo$
*/
#include "forwarding_api.h"
#include <xmmintrin.h>
#include <map>
#include <math.h>
using std::wstring;
static float sVolumeLevel = 1.f;
static bool sMute = false;
BOOL APIENTRY DllMain( HMODULE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
static bool initialized = false;
// do this only once
if (!initialized)
{ // bind to original winmm.dll
TCHAR system_path[MAX_PATH];
TCHAR dll_path[MAX_PATH];
::GetSystemDirectory(system_path, MAX_PATH);
// grab winmm.dll from system path, where it should live
wsprintf(dll_path, "%s\\winmm.dll", system_path);
HMODULE winmm_handle = ::LoadLibrary(dll_path);
if (winmm_handle != NULL)
{ // we have a dll, let's get out pointers!
initialized = true;
init_function_pointers(winmm_handle);
return true;
}
// failed to initialize real winmm.dll
return false;
}
return true;
}
extern "C"
{
// tracks the requested format for a given waveout buffer
struct WaveOutFormat
{
WaveOutFormat(int bits_per_sample)
: mBitsPerSample(bits_per_sample)
{}
int mBitsPerSample;
};
typedef std::map<HWAVEOUT, WaveOutFormat*> wave_out_map_t;
static wave_out_map_t sWaveOuts;
MMRESULT WINAPI waveOutOpen( LPHWAVEOUT phwo, UINT uDeviceID, LPCWAVEFORMATEX pwfx, DWORD_PTR dwCallback, DWORD_PTR dwInstance, DWORD fdwOpen)
{
if (pwfx->wFormatTag != WAVE_FORMAT_PCM
|| (pwfx->wBitsPerSample != 8 && pwfx->wBitsPerSample != 16))
{ // uncompressed 8 and 16 bit sound are the only types we support
return WAVERR_BADFORMAT;
}
MMRESULT result = waveOutOpen_orig(phwo, uDeviceID, pwfx, dwCallback, dwInstance, fdwOpen);
if (result == MMSYSERR_NOERROR
&& ((fdwOpen & WAVE_FORMAT_QUERY) == 0)) // not just querying for format support
{ // remember the requested bits per sample, and associate with the given handle
WaveOutFormat* wave_outp = new WaveOutFormat(pwfx->wBitsPerSample);
sWaveOuts.insert(std::make_pair(*phwo, wave_outp));
}
return result;
}
MMRESULT WINAPI waveOutClose( HWAVEOUT hwo)
{
wave_out_map_t::iterator found_it = sWaveOuts.find(hwo);
if (found_it != sWaveOuts.end())
{ // forget what we know about this handle
delete found_it->second;
sWaveOuts.erase(found_it);
}
return waveOutClose_orig( hwo);
}
MMRESULT WINAPI waveOutWrite( HWAVEOUT hwo, LPWAVEHDR pwh, UINT cbwh)
{
MMRESULT result = MMSYSERR_NOERROR;
if (sMute)
{ // zero out the audio buffer when muted
memset(pwh->lpData, 0, pwh->dwBufferLength);
}
else
{
wave_out_map_t::iterator found_it = sWaveOuts.find(hwo);
if (found_it != sWaveOuts.end())
{
WaveOutFormat* formatp = found_it->second;
switch (formatp->mBitsPerSample){
case 8:
{
char volume = (char)(sVolumeLevel * 127.f);
for (unsigned int i = 0; i < pwh->dwBufferLength; i++)
{
// unsigned multiply doesn't use most significant bit, so shift by 7 bits
// to get resulting value back into 8 bits
pwh->lpData[i] = (pwh->lpData[i] * volume) >> 7;
}
break;
}
case 16:
{
short volume_16 = (short)(sVolumeLevel * 32767.f);
// copy volume level 4 times into 64 bit MMX register
__m64 volume_64 = _mm_set_pi16(volume_16, volume_16, volume_16, volume_16);
__m64 *sample_64;
// for everything that can be addressed in 64 bit multiples...
for (sample_64 = (__m64*)pwh->lpData;
sample_64 < (__m64*)(pwh->lpData + pwh->dwBufferLength);
++sample_64)
{
//...multiply the samples by the volume...
__m64 scaled_sample = _mm_mulhi_pi16(*sample_64, volume_64);
// ...and shift left 1 bit since an unsigned multiple loses the most significant bit
// 0x7FFF * 0x7FFF = 0x3fff0001
// 0x3fff0001 << 1 = 0x7ffe0002
// notice that the LSB is always 0...should consider dithering
*sample_64 = _mm_slli_pi16(scaled_sample, 1);
}
// the captain has turned off the MMX sign, you are now free to use floating point registers
_mm_empty();
for (short* sample_16 = (short*)sample_64;
sample_16 < (short*)(pwh->lpData + pwh->dwBufferLength);
++sample_16)
{ // finish remaining samples that didn't fit into 64 bit register
*sample_16 = (*sample_16 * volume_16) >> 15;
}
break;
}
default:
// don't do anything
break;
}
}
}
return waveOutWrite_orig( hwo, pwh, cbwh);
}
void WINAPI setPluginVolume(float volume)
{
sVolumeLevel = volume;
}
void WINAPI setPluginMute(bool mute)
{
sMute = mute;
}
}
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